UTSA CS 3733 Operating Systems

CS 3733 Operating Systems, Page Replacment Review Solution

FIFO

1  2  3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  3  
-  -  -  -  -  -     -     -  -  -     -     -  -  -     
1  1  1  2  3  4  4  1  1  5  2  3  3  1  1  5  2  3  3  
   2  2  3  4  1  1  5  5  2  3  1  1  5  5  2  3  4  4  
      3  4  1  5  5  2  2  3  1  5  5  2  2  3  4  1  1

Number of page faults: 14 out of 19

LRU

1  2  3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  3  
-  -  -  -  -  -     -     -     -     -     -  -        
1  1  1  2  3  4  4  5  5  2  2  3  3  5  5  2  1  3  4  
   2  2  3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  
      3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  3

Number of page faults: 12 out of 19

Optimal

1  2  3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  3  
-  -  -  -     -           -           -        -        
1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  
   2  2  2  2  2  2  2  2  3  3  3  3  3  3  3  3  3  3  
      3  4  4  5  5  5  5  5  5  5  5  2  2  2  4  4  4

Number of page faults: 8 out of 19

Second Chance (reference bit set on entry)

1  2  3  4  1  5  1  2  1  3  1  5  1  2  1  3  4  1  3  
-  -  -  -  -  -     -     -     -     -     -  -  -     
1* 1* 1* 2  3  4* 4* 1  1* 2* 2* 1  1* 5* 5* 1  2  3* 3* 
   2* 2* 3  4* 1* 1* 5  5  1  1* 3  3  1  1* 2  3* 4* 4* 
      3* 4* 1* 5* 5* 2* 2* 3* 3* 5* 5* 2* 2* 3* 4* 1* 1*

Number of page faults: 13 out of 19